Many door closer assemblies are known which will cause a door to close once it has been opened. Many of these devices include either a linear or torsional resilient member which is increasingly distorted as the door is opened. The resilient member, e.g., a spring, generates a closing force which is preferably sufficient to close the door once it has been opened. The terms "spring" and "resilient member" will be used interchangably herein. It should be recognized that the "spring" of a door closer can be any kind of elastic or resilient member, including but not limited to conventional torsional or linear springs.
Generally, the spring of a door closer is interposed between two components or assemblies which are suitable for attaching to a door and a door frame. As the door is opened, the components move relative to one another causing the tension in the spring to gradually increase. As the tension in the spring increases, the closing force generated by the spring increases. The closing force acts on the first and second components to urge the door toward its closed position relative to the door frame. It should be noted that many door closers include a damping device, e.g., a pneumatic door "check," which is designed to control the closing velocity of the door.
It has generally been recognized that it is desirable to make the spring of a door closer adjustable so that the closing force created by the spring can be varied for any given door position. This adjustability feature is desirable in light of the various door weights, hinge designs, weather seal configurations and pneumatic check resistances which a door closer might encounter. If the closing force is too high, it is too difficult to distort the spring to open the door. The very young and the elderly might find it difficult to open the door in such cases. Also, if the closing force is too high, once the door is released it will tend to slam shut unless it is equipped with a check device which dissipates enough energy to adequately control the closing rate.
On the other hand, if the closing force produced by the resilient member of a door closer is insufficient, the door will tend to close too slowly, particularly if it is supplied with a pneumatic check. If the closing force is too weak any friction in the hinges might hinder or even prevent the closing of the door. Similarly, if the closing force is too weak, the door might not close with sufficient momentum to cause full engagement between the door and the weather seal typically carried by the door frame. Frictional forces are apt to increase over the lives of the door components as parts wear and as lubricants become exhausted. Also, temperature variations can detrimentally affect the smooth functioning of the door and associated components.
Thus, it is clear that an adjustable door closer is desirable. Theoretically there are at least two ways to alter the closing force produced by a resilient member of a door closer: the "spring rate" of the resilient member can be altered or the degree of tensioning or pretensioning of the spring can be changed. It is generally impractical to alter a spring's elastic constant. A spring can be readily prestressed, however, and this process typically results in a spring which supplies a closing force between the door and the door frame even when the door is in its fully closed position. Thus, changing the closing force of a door closer's resilient member, e.g., spring, is usually equivalent to changing the degree of pretension which the spring possesses in its closed state.
Door closers which possess the adjustability feature discussed above are generally known. However, the adjustment of known door closers often requires special tools not available to the typical homeowner, for example. Special tools are often needed since the resilient member of the typical door closer is a spring which has a relatively large spring rate. Such a spring typically acts on two components, the first of which might be attached to the door and the second of which might be attached to the door frame. The two components or assemblies are movable relative to one another. Therefore, in order to adjust the closing force generated by the spring a considerable amount of counterforce must typically be generated.
To generate the relatively large forces needed to adjust prior art door closers, the installer of the door often needs a special tool such as a spanner wrench, pin wrench or the like. As noted above, very often such tools are not readily available to the installer. For example, U.S. Pat. No. 4,050,115, issued to Joseph W. Gwozdz, shows a spring-loaded door hinge which can be pretensioned. However, to effect the pretensioning one must unlatch a component and twist a torsion rod and then relatch the component. Thus, the two components of the door closer which are acted upon by the spring remain movable relative to one another during the adjustment process. That is, in order to change the amount of closing force created by the spring the two components must be moved relative to one another while the spring continues to act on the two components. This requires that the person adjusting the hinge resist the closing force of the spring throughout the entire adjustment process.
Similarly, U.S. Pat. No. 3,426,387, issued to R. H. Bitney, shows a spring-loaded hinge which can be adjusted but which requires a spanner wrench for the adjustment process. Again, the two major components or assemblies of the spring-biased hinge remain movable with respect to one another throughout the adjustment process so that the spring tends to rotate them so as to close the door. It is perceived that such a spring, being under considerable tension and having a fairly substantial spring rate, is very difficult to resist or counter during the adjustment process.
To illustrate the difficulty by which many prior art door closers are adjusted, U.S. Pat. No. 2,066,795, issued to W. F. Moore, discloses and adjustment process that requires the holding of one of the components with one hand while the closer is readjusted and reclamped with the other hand. Clearly, this adjustment of the spring's pretension or closing force is difficult at least partly because the two major components or assemblies of the door closer remain movable throughout the adjustment process.
The present invention is directed to the shortcomings of the prior art door closers. More particularly, the door closer of the present invention includes a resilient member which can be easily adjusted to vary its closing force. When adjusting a preferred embodiment of the door closer of the present invention, no special tools are required. Further with regard to the present invention, during the adjustment process the two components acted upon the resilient member are locked so that the person making the adjustment need not work against the spring.
Thus, when the present invention is employed one can freely and easily associate a given spring tension with a plurality of door positions. When the door closer of the present invention is attached to a door and door frame and the door is opened to an arbitrary position, the tension in the spring is increased. This tension can be "stored" or "transferred" so as to be associated with a new door position and subsequently "restored." This "transfers" the tension to a new door position. Therefore, the door closer of the present invention allows one to easily increase or decrease the closing force by substantially eliminating relative motion between the two components which are operatively engaged by the closer's spring during the adjustment process.